KW Vision Centre

Sunglass Lenses

With summer just around the corner, sunglasses are a must for anyone looking to protect their eyes from the harmful ultraviolet rays of the sun.

Sunglasses have an extensive history. For example, Inuit people wore flattened walrus ivory “glasses,” that contained narrow slits to look through which helped to block the damaging reflective rays of the sun.

Also, It is said that the Roman emperor Nero liked to watch gladiator fights through emeralds. Unfortunately, these worked similarly to mirrors and did not in fact provide any protection from glare. In 12th-century China, however, it was noted that flat panes of smoky quartz were used to protect users’ eyes from glare. These “crystal sunglasses” were said to also be used by judges in ancient Chinese courts to hide facial expressions during the questioning of witnesses.

Modern sunglasses became popular in North America and Europe in the early 20th-century. Although often reserved for wealthier classes, and highly popular among movie stars, more affordable sunglass options became available around 1930. The invention of polarized lenses by Edwin H. Land in 1936 changed the sunglass landscape, making them not only fashionable, but also practical and a modern-day necessity.

Shopping for Sunglasses

The majority of sunglasses lenses today are made from a material called ‘polycarbonate’. Polycarbonate lenses, sometimes referred to as “poly” or “poly-carb”, naturally block the ultraviolet rays of the sun. They are, however, more susceptible to scratches. As a result, many companies have turned to higher-end material, such as glass, which offers superior optical quality and is naturally scratch-resistant.

Just like ophthalmic lenses, the quality of sunglass lenses is a very important factor. When wearing a pair of dark-tinted sunglasses, the pupils of our eyes dilate and essentially open up the eye, increasing the risk of UV-ray absorption. High quality sunglass lenses, such as Ray-Ban’s “G15 lenses”, have the capacity to reduce the harm caused from the sun’s rays, be it through better material, or polarized filters within the lenses. Poor quality sunglasses are not regulated, leaving the wearer vulnerable to damage within the eye caused by ultraviolet light.


The sun’s light vibrates and radiates outward in all directions. When the light is reflected off of a flat surface, such as a road or body of water, this light generally travels in a horizontal pattern. This is known as horizontal polarization. Polarization occurs both naturally and artificially. We see an example of natural polarization every time we look at a lake. The reflected glare off the surface is the light that does not make it through the “filter” of the water, and is the reason why we often cannot see anything below the surface, even when the water is very clear. This creates a visual obstacle and sometimes dangerous concentration of light which we experience as glare.

Polarized lenses will reduce glare from flat surfaces such as waterways and roads, decreasing glare and increasing visual clarity. While they have always been popular with water motorists and those who like to fish, the popularity of polarized lenses, such as those made by Oakley, has caught on with the broader public as they are ideal for almost all outdoor activities and every lifestyle.

Oakley sunglasses

Gradient Lenses

Gradient lenses are a popular sunglass tint option. Gradient lenses are recognized by the change, or graduation, of tint from the top to bottom of the lens. They begin with a darker tint at the top of the lens and gradually lighten towards the bottom. This style provides a more fashionable appearance and can also make reading while wearing sunglasses easier as the lower portion of the lens transmits more light.

UV Protection

Protection from ultraviolet, or “UV”, rays of the sun is one of the main reasons to wear sunglasses. The colour and cost of sunglasses does not determine the ability to block UV light. UV-blocking attributes can be found by choosing the right material, such as polycarbonate, glass, or hi-index lenses, which offer a denser material and naturally block UV rays, or by adding a UV-blocking chemical during manufacturing or through the addition of certain lens coatings.

The shape and fit of sunglasses can further aid protection from the sun. Sunglasses that offer a wraparound fit and sit closer to the wearer’s face can prevent UV-light from entering through the sides of the frame. Protective lenses are inhibited when the frame does not offer a proper fit.

The next time you’re in the market for a new pair of shades, be aware of your options and seek advice from your eye care professional. Inexpensive, poor quality sunglasses with labels wrongfully claiming to provide protection are not the best choice.

You have only one set of eyes, without any spares; take care of your vision.

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